Chris Sale was far from a polished pitcher by the time he was drafted by the White Sox. Armed with two above-average pitches, some analysts believed he was bound for the bullpen. But in his brief time in the minors, Sale worked on a devastating slider. The pitch was so effective that Sale scrapped what many scouts believed to be his most dominant pitch, his changeup, during his stint in the club’s bullpen. The slider continued to be a dominant force in the rotation during Sale’s 2012 breakout, and has become the pitch most people associate as Sale’s best weapon. The slider may be what Sale is known for, but the changeup has always been his best pitch.

Sale’s increased effectiveness of his changeup has been fairly subtle. His usage with the pitch has increased from from 14.78% to 20.14 % this season, most of which has come against lefties. Sale opted not to use his change against left-handers during 2012, but has started to use the pitch seven percent of the time against them in 2013. It’s something he uses when the batter is ahead in the count, but even then he only throws it 10% of the time. In a 34 pitch sample, it’s worked well. Against left-handers, Sale’s changeup his a 29.41% whiff rate. His willingness to go to the offering against lefties is at least partially responsible for his excellent .182 wOBA against them.

Against righties, Sale’s seen his slider slip. Sale’s whiff rate with his slider has dropped from 18.68% to 13.12%. In most scenarios, that would lead to decreased numbers against right-handers. Despite the decreased effectiveness of his slider, Sale has posted a nearly identical .296 wOBA against righties in 2013. The biggest reason for that, again, has been his changeup. There’s only been a small increase in whiff rate with the pitch, but the changeup has been useful in other ways.

Sale can rely on the pitch when he needs to get a strike. His usage with his changeup against righties is highest when the batter is ahead in the count, just like it is with lefties. This likely allows Sale to surprise hitters expecting fastballs. Against both righties and lefties, Sale’s 29.54 ball percentage is his lowest with any pitch. He’ll use the pitch to get himself back into the count. At that point, he reverts to using his fastball and slider.

The PITCH f/x pitch values agree. On a per rate basis, Sale’s change comes out on top. His 1.44 wCH/C is just higher than his 1.26 wSL/C (SL denotes a slider). What people don’t realize is that this was the case last season as well. Sale’s changeup was considered the better pitch using PITCH f/x. But since Sale relies on his slider to get punch-outs, that’s the pitch people associate with his dominance.

The increased reliance with his changeup has been one of the reasons for Sale’s improvement during his sophomore year in the rotation. In six fewer starts, Sale has almost matched his 4.7 WAR from 2012. The slider may be better suited for Sale’s highlight reel, but his changeup continues to be his most effective offering.